Preparation And Characterization Of Polycaprolactone Modified With Banana Nano Cellulose Fibers Blend Film

Banana fiber,one kind of natural fiber,widely planted in Guangxi province,so it possesses the advantages of wide source and renewable,in addition,it also exhibits low price and degradable.Due to environmentally friendly,bio-compatible,film forming and hydrophilic,cellulose nanofiber has potential application value in the fields of bio-materials,drug delivery and tissue engineering scaffold.Polycaprolactone?PCL?shows admirable bio-compatibility and bio-degradability,and it is usually utilized to tissue engineering scaffold,drug carrier.However,the obvious drawbacks of PCL?such as low mechanical strength,strong hydrophobicity,poor cell affinity?lead to it can't meet the requirements of the application fields in tissue engineering scaffold and drug carrier.This study focused on modifying PCL by banana cellulose nanofiber,and specific research contents and results are listed as follow:Obtained abandoned banana stem from around Nanning,and then banana fiber was extracted from banana stem through alkali method.The results show that the content of cellulose,hemicellulose,lignin,pectin,ash,water-soluble matter and fat wax are 51.4%,27.2%,10.1%,3.1%,4.2%,0.9%and 3.1%,respectively.Acid soaking,alkali treatment,acidolysis were implemented successively to prepare banana cellulose microcrystalline.Banana cellulose nanofiber?BNCF?was prepared via cation exchange resin method,subsequently,the particle size and morphology of BNCF were characterized by FTIR,TEM,DLS.The results of TEM indicate that banana cellulose prepared by acid treatment and alkali boiling reaches nanometer level.The results of DLS test illustrate that the average particle size of BNCF is 190.5 nm and its dispersion index is 0.671.The results of FTIR and XRD demonstrate that the crystallinity of microcrystalline cellulose decreases in the process of conversion.XRD results show that the banana cellulose nanofiber is cellulose type II.The high hydrophilic of BNCF decreases its dispersion in hydrophobicity polymer,so BNCF was dealt with surface grafting modification.The amphiphilic polymer BGCL was synthesized by ring opening graft polymerization of?-Cl monomer with ionic liquid Amim Cl as solvent,banana cellulose nanofiber hydroxyl as initiator and DMAP as catalyst.The grafting products were characterized by ¹HNMR,FTIR,XRD and CA.The results of FTIR and ¹HNMR show that BGCL polymer is successfully prepared in this experiment.The grafting ratio of BGCL increase with the increase of the molar ratio of glucose unit to caprolactone monomer.When the molar ratio reached1:60,the grafting ratio tend to be stable,which is 77.50%,and the further increase of the molar ratio has little change.The XRD result of BGCL polymer shows that the introduction of PCL side chain destroys the original crystalline structure of cellulose nanofiber.The results demonstrate that the contact angle of BGCL increases with the increase of grafting rate of the polymer,which is at least 9°smaller than that of pure PCL.PCL was blended with BNCF and BGCL respectively to prepare BNCF/PCL film and BGCL/PCL film.SEM results illustrate that the dispersion of BGCL in PCL is improved.POM test results indicate that the spherulite size of BNCF/PCL film is smaller than that of pure PCL,and the spherulite size of BGCL/PCL film is slightly larger than that of pure PCL.The tensile test results show that the tensile strength of the composite film can be improved when the ratio of BNCF and BGCL is in the range of 1%?3%.When the ratio of BNCF and BGCL is 3%,the tensile strength of BNCF/PCL film is 65.39%higher than that of pure PCL,the tensile strength of BGCL/PCL film is 90.01%higher than that of pure PCL,and the enhancement effect of BGCL is better than that of BNCF.The interface compatibility between modified BNCF and PCL is enhanced.The crystallization kinetics of PCL film,BNCF/PCL film and BGCL/PCL film was tested by DSC to investigate the effect of modification of BNCF on PCL crystallization performance.BNCF promotes the crystallization of BNCF/PCL film,the crystallization peak temperature of BNCF/PCL film is 4.11?higher than that of pure PCL,and the crystallinity of BGCL/PCL film is 5.34%higher than that of pure PCL.The crystallization peak temperature of BGCL/PCL film decreases slightly,but the crystallinity increases by 3.78%.In the selecte cooling rate range,the semi crystallization time of BNCF/PCL film is shortened with the addition of BNCF,and the crystallization rate is accelerated.The crystal growth mode of BNCF/PCL film accords with the three-dimensional growth of heterogeneous nucleation.The n value rang from 2.7 to 3.9,and the crystallization rate constant Z_c value increase first and then decrease.The half crystallization time of BGCL/PCL film decrease with the increase of BGCL at a low cooling rate of 2.5?/min.the cooling rate is between 5?/min and 12.5?/min.The T_1/2 ratio of BGCL/PCL film remaine unchanged with the increase of BGCL ratio.The crystal growth of BGCL/PCL film is a three-dimensional homogeneous nucleation with a n value range of 2?3.The crystallization rate constant Z_c value slightly increase with the increase of BGCL at 2.5?/min,indicating that the addition of BGCL at low cooling rate is helpful to accelerate the crystallization rate.In the range of 5?/min?12.5?/min,the Z_c value of BGCL/PCL film is almost the same as that of pure PCL,which shows that BGCL has little effect on the crystallization rate of BGCL/PCL film.The results are consistent with the semi crystallization time.